Remove CSV utils

These are in the utils repo since https://github.com/alphagov/notifications-utils/releases/tag/0.2.1

app/csv.py

@@ -1,12 +0,0 @@
-import csv
-
-
-def get_recipient_from_csv(file_data):
-    numbers = []
-    reader = csv.DictReader(
-        file_data.splitlines(),
-        lineterminator='\n',
-        quoting=csv.QUOTE_NONE)
-    for i, row in enumerate(reader):
-        numbers.append(row['to'].replace(' ', ''))
-    return numbers